How do I change file extension with javascript

问题

Does anyone know an easy way to change a file extension in Javascript?

For example, I have a variable with "first.docx" but I need to change it to "first.html".

回答1:

This will change the string containing the file name;

file = file.substr(0, file.lastIndexOf(".")) + ".htm";

For situations where there may not be an extension:

var pos = file.lastIndexOf(".");
file = file.substr(0, pos < 0 ? file.length : pos) + ".htm";

回答2:

file = file.replace(/\.[^.]+$/, '.html');

回答3:

In Node.js:

path.join(path.dirname(file), path.basename(file, path.extname(file)) + '.html')

This works also if the file doesn't have an extension and one of the parent directories has a dot in the name.

回答4:

This probably won't get many upvotes but I couldn't resist.

This code will deal with the edge case where a file might not have an extension already (in which case it will add it). It uses the "tilde trick"

function changeExt (fileName, newExt) {
  var _tmp
  return fileName.substr(0, ~(_tmp = fileName.lastIndexOf('.')) ? _tmp : fileName.length) + '.' + newExt
}

回答5:

var file = "first.docx";
file = file.split(".");
file = file[0]+".html";

来源：https://stackoverflow.com/questions/5953239/how-do-i-change-file-extension-with-javascript